JP2010037446A - Aqueous solution for clathrate hydrate formation, heat-storage agent, process for producing clathrate hydrate or slurry thereof, method for storing/radiating heat, and method for preparing aqueous solution for forming latent-heat-storage agent or major component thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-storage agent that can store a large quantity of cold heat in the temperature range of 3-15°C, is highly effective in preventing supercooling, and can retain the supercooling-preventing effect even when solidification and melting of the hydrate is frequently repeated, also to provide an aqueous solution that enables the formation of a clathrate hydrate serving as a principal component of the heat-storage agent, method for producing the clathrate hydrate, etc. <P>SOLUTION: The clathrate hydrate is produced by preparing an aqueous solution containing tri-n-butyl-n-pentyl ammonium bromide as a solute and tetra-iso-pentyl ammonium bromide as a supercooling inhibitor, wherein, the weight proportion of the tetra-iso-pentyl ammonium bromide to the tri-n-butyl-n-pentyl ammonium bromide is in a given range, then by cooling the aqueous solution to or below the hydrate forming temperature. The heat-storage agent contains the clathrate hydrate as a major component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat storage agent used in air-conditioning equipment such as air conditioning and cooling devices such as foods, a method for producing clathrate hydrate contained as a main component of the heat storage agent, and to produce the clathrate hydrate Relates to an aqueous solution of

The following terms are defined or interpreted as follows: The meaning or interpretation of this term does not preclude the technical scope of the present invention from reaching an equivalent scope.
(1) When a plurality of molecules combine to form a crystal under appropriate conditions, one molecule (host molecule) forms a cage, tunnel, layer, or network structure, and another molecule (guest molecule) in the gap ) In which a host molecule is a water molecule among compounds having a structure in which (
Even if the cage, tunnel, layer, or network structure of the water molecule that is the host molecule is incomplete, any compound that has a structure in which another molecule (guest molecule) enters the gap will be Included in “Japanese”. For convenience, the “clathrate hydrate” may be abbreviated as “hydrate”.

(2) “Hydrate formation temperature” refers to an equilibrium temperature at which clathrate hydrate is produced when an aqueous solution containing guest molecules of clathrate hydrate as a solute is cooled. Even when the temperature at which clathrate hydrate is generated varies depending on the concentration of guest molecules in the aqueous solution, this is referred to as “hydrate formation temperature”. When there are multiple types of clathrate hydrates with different guest molecules, the hydrate formation temperature often has a temperature range, so the horizontal axis is the temperature and the vertical axis is the specific heat. The peak value of specific heat in the graph is defined as “hydrate formation temperature”. For convenience, the “hydrate formation temperature” may be referred to as the “melting point” or “freezing point” of the hydrate.

(3) The aqueous solution may be referred to as a “raw material solution” in the sense that the clathrate hydrate is produced when the aqueous solution containing the guest molecule of the clathrate hydrate as a solute is cooled below the hydrate formation temperature. .
(4) “Harmonic melting point” refers to the case where the composition before and after phase change from an aqueous solution (liquid phase) to a hydrate (solid phase) does not change when a hydrate is produced by cooling the raw material solution (for example, Temperature when the hydrate having the same guest molecule concentration as that of the original aqueous solution is cooled and formed. Although the temperature (melting point) at which clathrate hydrate is generated varies depending on the concentration of guest molecules in the aqueous solution, the maximum point is the harmonic melting point in the state diagram in which the vertical axis indicates the melting point temperature and the horizontal axis indicates the concentration.
(5) “Harmonic concentration” refers to the concentration of a raw material solution that gives a harmonic melting point.
(6) “Harmonic aqueous solution” refers to a raw material solution having a concentration that provides a harmonic melting point.

(7) “Slurry” refers to a substance in which solid particles are dispersed or suspended in a liquid or a substance in that state. A surfactant may be added or mechanically stirred to make solid particles that tend to settle down, but as long as the solid particles are dispersed or suspended in the liquid, it is called “slurry”. As long as the solid particles are dispersed or suspended in the liquid, even if the dispersion or suspension is not uniform, it is referred to as “slurry”.

(8) “Heat storage agent” refers to a substance having an effect or property of storing heat energy and used for heat storage. As long as it has the effect or property of storing thermal energy and is a material used for heat storage, it is composed of multiple types of materials, whether it contains additives, liquid state, solid state or slurry state Regardless of whether it is used in a container, whether it is contained in a container or a capsule, etc., it is regarded as a “heat storage agent”. Among “thermal storage agents”, those that mainly store thermal energy corresponding to latent heat are “latent heat storage agents”, and those that mainly store sensible heat energy are “sensible heat storage agents”. There is a case.
The clathrate hydrate has an effect or property of accumulating heat energy corresponding to latent heat and is used for heat storage applications, and thus can be a “heat storage agent”, particularly a “latent heat storage agent”.

(9) The “main component” of the heat storage agent is a constituent component of the heat storage agent that contributes to the expression of the effect or property of accumulating the heat energy possessed by the heat storage agent or causes the expression thereof, and the component Therefore, the heat storage agent is used for heat storage applications. As long as it is such a component, whether it is composed of multiple types of substances, whether it contains additives, whether it is used in liquid state, solid state or slurry state, whether the amount is large or small Regardless of whether it is contained in a container or a capsule, it is regarded as the “main component” of the heat storage agent.
When the clathrate hydrate or slurry thereof is used as a heat storage agent or its “main component”, the guest molecules of the clathrate hydrate can be the “main component” of the heat storage agent.
When the harmonic aqueous solution of the clathrate hydrate guest molecule is cooled as a raw material solution, the composition does not change before and after the phase change from the liquid phase to the solid phase, and the harmonic aqueous solution itself changes into the clathrate hydrate. It looks like it is going. Focusing on this point, when clathrate hydrate is used as a heat storage agent or its “main component”, it can be said that the harmonious aqueous solution of the guest molecule is itself the “main component” of the heat storage agent. In particular, after cooling and solidifying, it can be said that the heat storage agent itself.
The “main component” of the heat storage agent may be referred to as “the main component of the heat storage agent”.

  Since the latent heat storage agent has advantages such as a higher heat storage density than the sensible heat storage agent, a constant phase change temperature, and a stable heat extraction temperature, it has been put to practical use in various applications. For example, in an air conditioning system, a reduction in pump power for transporting a heat medium is required in order to reduce equipment costs and operating costs, and in order to increase heat transport density, a latent heat storage agent having a high heat storage density is used. It is being considered.

As such a latent heat storage agent, a clathrate hydrate of a tetraalkylammonium compound is known (Patent Document 1, Patent Document 2).
The clathrate hydrate of tetraalkylammonium compound has a large latent heat during its generation, so it has a relatively large amount of heat storage and is not flammable like paraffin, so it is easy to handle and is a very useful heat storage agent. It is. In addition, the clathrate hydrate of the tetraalkylammonium compound has a harmonic melting point higher than 0 ° C., which is the melting point of ice, so the temperature of the refrigerant when the heat storage agent is cooled to produce a hydrate may be high, There is also an advantage that the coefficient of performance (COP) of the refrigerator is increased and energy can be saved (Patent Document 3).

  When the raw material solution is cooled to reach the hydrate formation temperature (melting point or freezing point) and reach a lower temperature, the hydrate is not generated and the state or phenomenon in which the aqueous solution is maintained is supercooled or supercooled. This phenomenon (hereinafter sometimes referred to simply as “supercooling”) is used. However, when a hydrate is used as a heat storage agent, if the degree of supercooling, that is, the degree of supercooling is large, the cooling temperature of the raw material solution (depending on the refrigerant) When cooling, the refrigerant temperature) must be lowered, and the formation of hydrates is delayed. Therefore, it is important to make the degree of supercooling as small as possible to prevent or suppress supercooling (hereinafter, simply referred to as “supercooling prevention”) (see Patent Document 4).

  Conventionally, for example, by mixing fine particles into a raw material solution and causing it to function as a nucleation material of hydrate (Patent Document 5), or a drug having an effect or property of preventing supercooling, that is, a supercooling inhibitor Attempts have been made to prevent or suppress overcooling by adding to the raw material solution.

Japanese Patent Publication No.57-35224 Japanese Patent No. 3641362 JP 2007-40641 A JP 2001-343139 A Japanese Patent No. 3407659

  However, in the method of Patent Document 5 in which fine particles are mixed in the raw material solution, the effect of preventing overcooling does not spread widely to the raw material solution unless the fine particles are uniformly dispersed in the raw material solution, and it takes time to manifest. There is a problem that it takes time, and if the formation or coagulation and melting of the hydrate is repeated, the fine particles are separated from the raw material solution and the effect of preventing overcooling is lost.

  On the other hand, there is a problem with the latter method of adding a supercooling inhibitor to the raw material solution. For example, in the case where supercooling occurs or when supercooling is expected and supercooling inhibitor is supplied to the raw material solution, a problem similar to that in the case of adding fine particles occurs. That is, even if the supercooling inhibitor is supplied to the raw material solution in a timely manner, the supercooling inhibitor does not immediately spread over the entire aqueous solution. Therefore, it takes time until the supercooling prevention effect reaches the entire aqueous solution. Cooling cannot be prevented or suppressed sufficiently or in a short time. The problem is that it is necessary to prevent the clathrate hydrate formation time from changing every time the heat is stored (in other words, the clathrate hydrate formation is stable) If it is necessary to rapidly produce clathrate hydrates from the need to do in step 1, it becomes a big problem to be solved. Therefore, if there is a supercooling preventive agent that produces an effect of preventing supercooling if it is first added to the raw material solution, it will not be damaged.

  However, the initial preparation was made that the amount of the supercooling inhibitor added to the raw material solution was inappropriate even if the supercooling inhibitor was added to the raw material solution at first, even if the effect of preventing the supercooling would occur. There are cases where the hydrate formation temperature of the raw material solution changes excessively or the amount of heat storage that is planned cannot be secured. Further, the effect of preventing overcooling does not necessarily deteriorate with time. For example, in the actual use environment of the heat storage agent, heat storage and heat dissipation (hereinafter sometimes collectively referred to as “storage heat dissipation”), that is, clathrate hydrate generation or solidification and melting are frequently repeated. Such repeated heat storage and heat dissipation may cause deterioration of the overcooling prevention effect over time.

  On the other hand, the inventors supercooled in a short time by adding tetranbutylammonium fluoride (TBAF) or its aqueous solution as a supercooling release agent to a heat storage agent mainly composed of tetranbutylammonium bromide aqueous solution. Has been found that heat storage can be performed in a short time, and that overcooling prevention effects do not deteriorate over time even when heat storage and heat release are repeated frequently. (Japanese Patent Laid-Open No. 2007-246778)

On the other hand, tetra-n-butylammonium fluoride contains fluorine, so that it becomes a fluorine ion in an aqueous solution and tends to corrode metals such as aluminum and carbon steel. Regarding the corrosion problem, the inventors have found that a deoxidation type corrosion inhibitor such as sodium salt or lithium salt of sulfite or thiosulfate is effective for inhibiting corrosion.
This method of adding a deoxidizing type corrosion inhibitor is effective when the environment in which the heat storage agent is used is an environment where air and oxygen are blocked, but the heat storage agent to which tetra nbutylammonium fluoride is added is used. When air or oxygen invade into the environment to be intermittently or continuously, or when the heat storage agent is used in the open air, there is a deoxidizing corrosion inhibitor in an amount corresponding to the amount of oxygen present. So as to maintain the concentration. When intrusion of air or oxygen continues over a long period of time, adding a deoxidizing corrosion inhibitor correspondingly accumulates reaction products of the deoxidizing corrosion inhibitor and oxygen, and the composition balance of the heat storage agent May collapse, causing a change in melting point, a decrease in the amount of latent heat in the operating temperature range, and a decrease in the effect of preventing overcooling.

  Other corrosion inhibitors include polyphosphate, tripolyphosphate, tetrapolyphosphate, dihydrogen phosphate, pyrophosphate or metasilicate sodium salt, potassium salt, calcium salt, lithium salt, etc. There is a type of corrosion inhibitor, but when air or oxygen enters the environment where the heat storage agent is used intermittently or continuously, or when the heat storage agent is used in the open atmosphere, sufficient corrosion inhibition performance is achieved. It may not be demonstrated.

  The present invention has been made to solve the above-described problems. When the clathrate hydrate is produced by cooling the raw material solution, the degree of supercooling of the raw material solution is reduced or the supercooling is prevented. Technology that can be suppressed, technology that can make it difficult to reduce the effect of preventing overcooling even when hydrate formation or solidification and melting in a raw material solution is repeated frequently are provided, and technology related thereto The purpose is to do.

  The aqueous solution for clathrate hydrate formation according to the first aspect of the present invention contains tri-n-butyl-n-pentylammonium bromide (TBPAB) as a solute, and tetraisopentylammonium bromide (TiPAB) is a supercooling inhibitor. It is characterized by being added as.

The aqueous solution for clathrate hydrate formation according to the second aspect of the present invention is the aqueous solution according to the first aspect, and tetraisopentyl bromide for an aqueous solution containing tri-n-butyl-n-pentylammonium bromide as a solute. The weight ratio of ammonium is 0.5% or more and 5.0% or less.

The aqueous solution for clathrate hydrate production according to the third aspect of the present invention is the aqueous solution according to the first aspect, wherein the concentration of tri-n-butyl-n-pentylammonium bromide is 15 wt% or more and 34.1 wt%. %, And the weight ratio of tetraisopentylammonium bromide to an aqueous solution containing tri-n-butyl-n-pentylammonium bromide as a solute is 0.5% or more and 5.0% or less. .

  An aqueous solution for clathrate hydrate formation according to a fourth aspect of the present invention is an aqueous solution according to any one of the first to third aspects, and a corrosion inhibitor is added thereto. Is.

  The heat storage agent according to the fifth aspect of the present invention is produced by cooling an aqueous solution for clathrate hydrate production according to any one of the first to fourth aspects to a hydrate production temperature or lower. Including clathrate hydrate.

  The heat storage agent according to the sixth aspect of the present invention is produced by cooling the clathrate hydrate producing aqueous solution according to any one of the first to fourth aspects to a hydrate production temperature or lower. The clathrate hydrate contains a slurry formed by dispersing or suspending the clathrate hydrate in an aqueous solution or an aqueous solvent.

  The heat storage agent according to the seventh aspect of the present invention is characterized by comprising tri-n-butyl-n-pentylammonium bromide, tetraisopentylammonium bromide as a supercooling preventing agent, and water.

  The heat storage agent according to the eighth aspect of the present invention is the heat storage agent according to any one of the fifth to seventh aspects, and is characterized in that a corrosion inhibitor is added.

  The method for producing a clathrate hydrate or slurry thereof according to the ninth aspect of the present invention comprises the steps of preparing an aqueous solution for clathrate hydrate production according to any one of the first to fourth aspects, And cooling the aqueous solution to form clathrate hydrate.

  The heat storage and release method according to the tenth aspect of the present invention is to cool the aqueous solution for clathrate hydrate generation according to any one of the first to fourth aspects, thereby generating clathrate hydrate. The thermal energy is accumulated, and the generated clathrate hydrate is melted to release the thermal energy.

  The method for preparing an aqueous solution for producing the latent heat storage agent or the main component thereof according to the eleventh aspect of the present invention includes a step of adding tetraisopentylammonium bromide to an aqueous solution of tri-n-butyl-n-pentylammonium bromide. It is characterized by having.

The preparation method of the aqueous solution for producing the latent heat storage agent or the main component thereof according to the twelfth aspect of the present invention is the preparation method according to the eleventh aspect, and is an aqueous solution of tri-n-butyl-n-pentylammonium bromide. The weight ratio of tetraisopentylammonium bromide is 0.5% or more and 5.0% or less.

  An aqueous solution for generating a latent heat storage agent or a main component thereof according to the thirteenth aspect of the present invention is an aqueous solution that is cooled to generate clathrate hydrate, and contains tri-n-butyl-n-pentylammonium bromide as a solute. In addition, tetraisopentylammonium bromide is added, the concentration of tri-n-butyl-n-pentylammonium bromide is 15 wt% or more and 34.1 wt% or less, and tri-n-butyl n-pentyl ammonium bromide is contained as a solute. The weight ratio of tetraisopentylammonium bromide to the aqueous solution is 0.5% or more and 5.0% or less.

  The latent heat storage agent according to the fourteenth aspect of the present invention, or the clathrate hydrate which is the main component thereof or the slurry thereof, comprises the steps of preparing the aqueous solution according to the thirteenth aspect, and cooling the aqueous solution. And a step of producing an clathrate hydrate.

(1) According to the present invention, tetraisopentylammonium bromide is added to an aqueous solution containing tri-n-butyl-n-pentylammonium bromide as a solute. When it produces | generates by cooling of aqueous solution, overcooling can be prevented or suppressed. Tetraisopentylammonium bromide is added so that the weight ratio of tetraisopentylammonium bromide to an aqueous solution containing tri-n-butyl-n-pentylammonium bromide as a solute falls within a predetermined range, so that it is possible to prevent overcooling. It is excellent, and the decrease in the latent heat amount in the temperature range of 3 to 15 ° C. due to the addition can be made within a practical fluctuation allowable range. Moreover, even if the production | generation of a hydrate in a raw material solution or coagulation | solidification and melting | fusing is repeated frequently, the fall of a supercooling prevention effect can be made hard to occur.

  Therefore, according to the present invention, the generation of an aqueous solution or hydrate for generating a clathrate hydrate having a reduced degree of supercooling or hardly causing supercooling or for generating a heat storage agent or its main component. Alternatively, an aqueous solution (first to fourth and thirteenth) for generating a clathrate hydrate or for generating a heat storage agent or its main component, in which the effect of preventing overcooling hardly occurs even when solidification and melting are repeated frequently. ), A heat storage agent containing each clathrate hydrate that can be produced from the raw material solution while preventing or suppressing supercooling (or each of the clathrate hydrate slurries (the fifth and sixth forms)), A heat storage agent (seventh and eighth forms) that can be produced while preventing or suppressing supercooling, a method for producing clathrate hydrate or a slurry thereof while reducing the degree of supercooling or preventing or suppressing supercooling (Ninth embodiment) Formation of hydrate in raw material solution Is a heat storage / dissipation method in which the effect of preventing overcooling hardly occurs even when solidification and melting are repeated frequently (tenth embodiment), a latent heat storage agent that can be generated from a raw material solution while preventing or suppressing overcooling, or its main A clathrate hydrate as a component or a method for producing a slurry thereof (fourteenth embodiment) can be realized. Moreover, the preparation method (11th and 12th form) of the aqueous solution for producing | generating the latent heat storage agent or its main component which becomes easy to adjust so that the amount of latent heat per unit weight of a thermal storage agent may become larger. Can be realized.

  Details of the functions and effects of the present invention and the functions and effects unique to the embodiment or the embodiments will be described later.

(2) Since tri-n-butyl-n-pentylammonium bromide and tetraisopentylammonium bromide have bromine ions, they are corrosive. Therefore, according to the fourth and eighth embodiments of the present invention, since the corrosion inhibitor is also added to the raw material solution, an aqueous solution for clathrate hydrate generation and a heat storage agent that are inhibited from corrosion are realized. can do.

  Further, according to the present invention, tetraisopentylammonium bromide is added as an anti-cooling agent to an aqueous solution containing tri-n-butyl-n-pentylammonium bromide as a solute. In the case of adding ammonium, the addition amount of the corrosion inhibitor can be reduced as compared with the case where it is necessary to add a large amount of the corrosion inhibitor because it has highly corrosive fluorine ions. According to the present invention, since the amount of the corrosion inhibitor added can be reduced, the problem that occurs when tetra-n-butylammonium fluoride is added as a supercooling inhibitor, that is, air or oxygen is intermittent in the environment where the heat storage agent is used. Or it must be added to maintain the concentration of the corrosion inhibitor in response to continuous intrusion, the reaction product of the corrosion inhibitor accumulates, the composition balance of the heat storage agent collapses, the melting point changes, It is possible to prevent problems such as a decrease in the amount of latent heat in the operating temperature range and a decrease in the overcooling prevention function.

  As a corrosion inhibitor that can be employed in the present invention, a deoxidation type corrosion inhibitor that consumes dissolved oxygen to suppress corrosion when the heat storage agent is used in a sealed environment, that is, an environment where dissolved oxygen does not enter. Specific examples include sodium salt and lithium salt of sulfite or thiosulfate, and at least one corrosion inhibitor selected from these can be added to the heat storage agent to suppress corrosion. .

In addition, as another corrosion inhibitor applicable to a sealed environment, there is a film-forming type corrosion inhibitor that forms a film that prevents corrosion on a metal surface and suppresses corrosion, specifically, polyphosphate. , Tripolyphosphate, tetrapolyphosphate, dihydrogen phosphate, pyrophosphate or metasilicate sodium salt, potassium salt, calcium salt, lithium salt, at least one selected from among these An agent can be added to the heat storage agent to suppress corrosion.
Corrosion can be further suppressed by using these film-forming corrosion inhibitors in combination with the above-described deoxidizing corrosion inhibitor sulfites or thiosulfates.
Further, other corrosion inhibitors applicable to the sealed environment include nitrite, benzotriazole, hydrazine, erythorbate, ascorbate, and saccharide.

When the heat storage agent is used in an open air environment, bromide or sulfate of zinc, magnesium or calcium can be used as a corrosion inhibitor in the open air environment. By adding at least one type of corrosion inhibitor selected from these, hydroxide ions and carbonate ions contained in the solution of the heat storage agent, and zinc ions, magnesium ions or calcium ions of the corrosion inhibitor are added. This results in the formation of carbonates and hydroxides, which can be deposited on the metal surface to form a film to suppress corrosion, and these corrosion inhibitors act as film-forming corrosion inhibitors. Yes.
Add the aforementioned bromide or sulfate of zinc, magnesium or calcium to the heat storage agent, and then add at least one phosphate selected from phosphates such as sodium, potassium, lithium, etc. Acid ions and zinc ions, magnesium ions, or calcium ions are combined to form a phosphate, and this phosphate is deposited on the surface of the metal material to form a coating, thereby inhibiting corrosion. Since phosphates such as sodium, potassium, and lithium have high solubility, they can efficiently form a film and suppress corrosion. The phosphate ions that form the precipitation film have a more effective effect. Since phosphate also acts as a pH adjusting agent, it is possible to prevent the pH from being lowered due to dissolution of carbon dioxide from the atmosphere or hydrolysis of corrosion products.

  By adding the above-described corrosion inhibitor to the heat storage agent, it is possible to provide a heat storage agent with less corrosivity without greatly changing the melting point and the heat storage amount.

(3) The heat storage agent according to the present invention, in particular the latent heat storage agent, has a high effect of preventing overcooling and can maintain the effect of preventing overcooling even when hydrate formation or solidification and melting are repeated frequently. A lot of cold energy can be accumulated in a temperature range of 3 to 15 ° C. For this reason, the heat storage agent according to the present invention is particularly promising as a heat storage agent for air conditioning.

The reason why the latent heat storage agent capable of storing heat in the temperature range of 3 to 15 ° C. is suitable for air conditioning applications is as follows.
That is, in air conditioning using a latent heat storage agent, heat exchange between the heat storage agent storing the cold heat from the cold source as latent heat and the air of the air conditioning load is performed directly or through a medium, and the air after the heat exchange is air-conditioned. By sending it to the target space, the temperature and humidity of the space are adjusted. In many cases, the temperature of the cold air blown out from the indoor unit in the cooling air-conditioning is generally about 15 ° C., and at most about 17 ° C. If the temperature is higher than that, it is difficult to obtain the same level of air-conditioning effect unless the amount of air to be sent out toward the space to be air-conditioned is increased. On the contrary, the air-conditioning efficiency is lowered. Therefore, the latent heat storage agent that supplies cold heat to cold air is required to be capable of storing latent heat of 15 ° C. or less in consideration of a temperature difference (about 2 ° C.) necessary for heat exchange with air. . In addition, in the case of ice, which is a typical example of a latent heat storage agent for air conditioning, it is necessary to cool at a temperature lower than 0 ° C., so the COP of the refrigerator becomes low, the energy required for cold storage increases, and energy saving cannot be achieved. There is a problem. In order to maintain COP at a high level and realize energy saving, the latent heat storage agent for air conditioning is required to be able to store heat at 5 ° C or higher and at least 3 ° C or higher. Therefore, the latent heat storage agent that can store heat in the temperature range of 3 to 15 ° C. is suitable for air conditioning applications.

However, a heat storage agent capable of storing thermal energy in the temperature range of 3 to 15 ° C. must be able to withstand actual use regardless of whether it is used for air conditioning.
For example, there is a heat storage agent (melting point: 10 to 25 ° C.) in which polyglycerin is added to a hydrate-based heat storage agent main component containing trimethylolethane, water, and urea. This heat storage agent is described in detail in Japanese Patent Application Laid-Open No. 2000-256659, but as long as it is described, the number of times of confirming the repetition of solidification and melting is limited to about 100 at most. With this number of repeated uses, the purpose of use is limited, and the effect of preventing overcooling can occur if separation of component substances in the aqueous solution, concentration deviation, or phase separation between the hydrate formed by cooling and the parent phase occurs. It is difficult to say that it can withstand widespread actual use (especially for private use).

  On the other hand, the heat storage agent according to the present invention contains tri-n-butyl-n-pentylammonium bromide, tetraisopentylammonium bromide and water, and the aqueous solution for producing a hydrate according to the present invention contains tri-n-butyl n-bromide. It contains pentylammonium and tetraisopentylammonium bromide, respectively. Tri-n-butyl-n-pentylammonium bromide accumulates thermal energy corresponding to latent heat in a temperature range of 3 to 15 ° C. when in an aqueous solution state. The hydrate formation temperature does not change greatly even when a small amount of tetraisopentylammonium bromide is added. When the clathrate hydrate is generated from the raw material solution containing tetraisopentylammonium bromide as an additive, the degree of supercooling of the raw material solution is reduced or the supercooling is prevented or suppressed. Moreover, the effect of preventing overcooling does not decrease even if the formation or solidification and melting of the hydrate is repeated 1000 times or more in the raw material solution.

  Therefore, according to the present invention, it is possible to accumulate heat energy in the temperature range of 3 to 15 ° C., and to achieve a particularly beneficial effect that a heat storage agent that can withstand practical use can be realized.

  According to the present invention, a heat storage agent that can store heat in a temperature range of 3 to 15 ° C (latent heat), an aqueous solution having a hydrate formation temperature in a range of 3 to 15 ° C, and the like can be realized. The invention is not limited to air conditioning applications. Regardless of whether or not the present invention is used for air conditioning, a heat storage agent capable of storing thermal energy in the temperature range of 3 to 15 ° C, an aqueous solution having a hydrate formation temperature in the range of 3 to 15 ° C, and the like. It is a technical idea that can be realized. I'll add this point just in case.

Hereinafter, the present invention will be described in detail by embodiments.
For convenience, tri-n-butyl-n-pentylammonium bromide may be abbreviated as “TBPAB” and tetraisopentylammonium bromide may be abbreviated as “TiPAB”.

1. New knowledge related to the present invention will be described. Some forms of the invention are based on this new knowledge.
(A) Tri-n-butyl-n-pentylammonium bromide forms clathrate hydrate, and its harmonic melting point is about 7 ° C., and the latent heat at this harmonic melting point is 200 kJ / kg. Regarding a heat storage agent containing clathrate hydrate containing tri-n-butyl-n-pentylammonium bromide as a guest molecule (particularly a heat storage agent containing clathrate hydrate as a main component), tri-n-butyl n-pentylammonium bromide as a solute Investigate substances capable of exerting or maintaining the effect of preventing or suppressing the supercooling that occurs when cooling the raw material solution contained therein, and their composition, and adding tetraisopentylammonium bromide or an aqueous solution thereof as the substance I found it effective.

Although the patentability of the present invention is not predicted based on any theory, it is possible to prevent overcooling by adding tetraisopentylammonium bromide to a raw material solution containing tri-n-butyl-n-pentylammonium bromide as a solute. If the reason for playing is estimated, it is as follows.
In other words, tetraisopentylammonium bromide has a hydrated melting point of 28 ° C., and the melting point of hydrate or trinbutylbromide produced from a raw material solution containing tri-n-butyl-n-pentylammonium bromide as a solute. It is sufficiently higher than the melting point of n-pentylammonium hydrate. Therefore, when the above raw material solution is cooled, tetraisopentylammonium bromide hydrate is formed prior to tri-n-butyl n-pentylammonium bromide hydrate. Then, the tetraisopentylammonium bromide hydrate becomes a nucleus (product nucleus) that triggers or induces the formation of tri-n-butyl-n-pentylammonium bromide hydrate, and the hydrate that is the main component of the heat storage agent is As a result of generating in a short time, overcooling is prevented or suppressed. Tetraisopentylammonium bromide hydrate is a related substance of tri-n-butyl-n-pentylammonium bromide hydrate, compatible, and similar in crystal structure. Prevented or suppressed.

Tetraisopentylammonium bromide has a lower affinity for water than tetranbutylammonium fluoride, where the alkyl constituting the molecule is isopentyl and the alkyl is nbutyl. There is a tendency to easily form clathrate hydrates from the existing state. From such a tendency, when the raw material solution obtained by adding tetraisopentylammonium bromide to an aqueous solution of tri-n-butyl-n-pentylammonium bromide is cooled, tetra-n-butylammonium fluoride is added to the aqueous solution of tri-n-butyl-n-pentylammonium bromide. Compared to the case where the added raw material solution is cooled to produce tetra-n-butylammonium fluoride hydrate, tetraisopentylammonium bromide hydrate is rapidly produced. It becomes a nucleus (product nucleus) that triggers or induces the formation of tri-n-butyl-n-pentylammonium bromide hydrate, and supercooling is effectively prevented or suppressed.
The tendency for such tetraisopentylammonium bromide to form hydrates compared to tetra-n-butylammonium fluoride means that it is more effective as a supercooling inhibitor, and it also has an odor. The amount of tetraisopentylammonium bromide added to the aqueous solution of tri-n-butyl-n-pentylammonium bromide as a supercooling inhibitor can be reduced compared to the case of adding tetra-n-butylammonium fluoride as a supercooling inhibitor. Moreover, the adverse effect on the thermal properties of the hydrate or the heat storage agent containing this as a main component due to the addition of the supercooling inhibitor can be minimized.

(Ii) Regarding the addition amount of tetraisopentylammonium bromide as a supercooling preventive agent, for example, the weight ratio (percentage) of tetraisopentylammonium bromide to the aqueous solution of tri-n-butyl-n-pentylammonium bromide is predetermined. It is preferable to add so as to be within the range. When the amount is less than the lower limit of the predetermined range, the amount of tetraisopentylammonium bromide hydrate is reduced, and it becomes difficult to form a nucleus of tri-n-butyl-n-pentylammonium bromide hydrate, thereby preventing overcooling. Is lacking. On the other hand, if it exceeds the upper limit of the predetermined range, a hydrate produced from an aqueous solution containing tri-n-butyl n-pentyl ammonium bromide and tetra-iso-pentyl ammonium bromide or tri-n-butyl n-pentyl ammonium bromide and odor The amount of latent heat that can be stored in a temperature range of 3 to 15 ° C. is significantly reduced due to the influence of the latent heat amount of the hydrate containing tetraisopentylammonium bromide, and thus the heat storage agent mainly composed of the hydrate. End up.
Therefore, by making the addition of tetraisopentylammonium bromide in an appropriate amount (or in an appropriate amount range), it is possible to reduce the adverse effect on the thermal properties of the main component of the heat storage agent as much as possible by adding an anti-cooling agent, while supercooling. The effect of prevention can be made more reliable or effective.

2. Next, the addition of tetraisopentylammonium bromide as a supercooling inhibitor and the effect thereof will be described more specifically.
<Measurement and evaluation method>
(A) Tetraisopentylammonium bromide addition ratio to an aqueous solution of tri-n-butyl-n-pentylammonium bromide prepared to a certain concentration (tetraisopentylammonium bromide added to tri-n-butyl-n-pentylammonium bromide aqueous solution) The aqueous solution (raw material solution) for producing the hydrate is prepared by changing the weight ratio) (the hydrate produced by cooling the aqueous solution is dispersed in the aqueous solution or by itself. A heat storage agent (particularly a latent heat storage agent) or a main component thereof as a slurry obtained by suspending. A raw material solution in which tetraisopentylammonium bromide is not added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide is also prepared.
For tri-n-butyl-n-pentylammonium bromide aqueous solution, the latent heat amount of the hydrate produced by cooling when the concentration is the harmonic concentration is maximized, so the odor of the harmonic concentration (34.1% by weight) is the first. A raw material solution in which tetraisopentylammonium bromide was added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide was prepared and evaluated, and then 30% to 15% by weight of an aqueous solution of tri-n-butyl-n-pentylammonium bromide with tetramethylene bromide was evaluated. A raw material solution to which isopentylammonium was added was also prepared and evaluated.

  About the hydrate produced | generated by cooling each raw material solution prepared as mentioned above, the supercooling prevention property shown below, a latent heat amount, and a latent heat amount ratio are measured and evaluated. Through this measurement and evaluation, a preferable addition rate of tetraisopentylammonium bromide (tri-n-butyl-n-pentylammonium bromide aqueous solution), which is highly effective in preventing supercooling and has a small decrease in latent heat in the temperature range of 3 to 15 ° C. The range of the weight ratio of tetraisopentylammonium bromide added to (hereinafter sometimes referred to as “TiPAB addition rate”) is determined.

(1) Supercooling prevention property The raw material solution prepared according to the above procedure was cooled at 3 ° C for 24 hours to examine whether or not hydrate crystals were formed. If a hydrate crystal is formed, it is evaluated that an effect of preventing the overcooling or preventing the overcooling is recognized. Further, this raw material solution was cooled to 3 ° C. to form a hydrate, and then heated to 40 ° C. to melt the formed hydrate, and the hydrate formation or solidification and melting were repeated 1000 times. When it is recognized that there is no deterioration in the supercooling prevention property, it is evaluated that there is no deterioration in the supercooling prevention performance or that the supercooling prevention effect is durable.

(2) Latent heat quantity and latent heat quantity ratio A differential scanning calorimeter (DSC) measurement of the raw material solution prepared by the above procedure is performed to measure the latent heat quantity. The raw material solution prepared by the above procedure is heated and cooled according to the following procedure, and the amount of latent heat is obtained by measuring the amount of heat at the time of melting of the solid phase produced by cooling in the temperature range of 3 to 15 ° C. . The amount of latent heat here refers to heat energy corresponding to latent heat in a temperature range of 3 to 15 ° C.
1) Heat the sample to 15 ° C. at a heating rate of + 5 ° C./min and hold the sample at 15 ° C. for 5 minutes.
2) The sample is cooled from 15 ° C. to 3 ° C. at a cooling rate of −5 ° C./min, and the sample is held at 3 ° C. for 5 minutes.
3) Heat the sample from 3 ° C to 15 ° C at a heating rate of + 5 ° C / min and hold the sample at 15 ° C for 5 minutes.

  A temperature of 3 to 15 ° C. of a hydrate formed by cooling a raw material solution in which tetraisopentylammonium bromide is added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide prepared to a certain concentration while changing the addition rate. The latent heat of fusion in the range was measured using DSC, the latent heat at the TiPAB addition rate that showed the highest latent heat was set to 1, and the ratio of the latent heat at other TiPAB addition rates to this is the latent heat amount ratio. The change in the amount of latent heat when the addition rate of tetraisopentylammonium bromide is changed by the ratio is evaluated.

<Results of measurement and evaluation>
(I) 34.1 wt% aqueous solution of tri-n-butyl-n-pentylammonium bromide An aqueous solution (harmonic aqueous solution) having a concentration (34.1 wt-%) that gives a harmonic melting point of tri-n-butyl-n-pentylammonium bromide An aqueous solution for hydrate formation was prepared by adding tetraisopentylammonium. More specifically, a plurality of raw material solutions having different ratios (% by weight) of tetraisopentylammonium bromide to the weight of tri-n-butyl-n-pentylammonium bromide aqueous solution (wt%) (TiPAB addition rate) are prepared, and thus prepared. The measurement and evaluation described in (1) and (2) above were performed on each raw material solution. The results are shown in Table 1.
If there is an effect of preventing overcooling or preventing overcooling, and no decrease is observed after 1000 times of solidification and melting, ○ is not released, and hydrate crystals are not formed without overcooling being released. In this case, that is, when there is no supercooling effect or overcooling prevention property or when a decrease is observed, x is marked, and when the overcooling effect or overcooling prevention property is partially recognized, Δ is marked. .
In addition, when the supercooling was not released and hydrate crystals were not formed, the amount of latent heat could not be measured.

Table 1 shows the following.
[A] When the addition ratio of TiPAB is less than 0.25% by weight with respect to a 34.1% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, there is no effect of preventing overcooling.
[B] With respect to a 34.1% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, the amount of latent heat is maximum when the addition rate of TiPAB is 0.5% by weight. The latent heat ratio is greatly reduced and exceeds the practical fluctuation tolerance (20%) when the hydrate is used as a heat storage agent or its main component.

The result of the above [b], that is, the result that the latent heat amount in the temperature range of 3 to 15 ° C. depends on the addition rate of TiPAB is unpredictable from the conventional knowledge. Therefore, the reason why the amount of latent heat is reduced was examined.
As a result of analyzing the DSC measurement results, when the TiPAB addition ratio is greater than 5.0% by weight, the range having latent heat tends to move to the high temperature side. This phenomenon is presumed to be the reason why the amount of latent heat in the temperature range of 3 to 15 ° C. decreases when the TiPAB addition rate exceeds 5.0% by weight.

  From the above results, when adding tetraisopentylammonium bromide to an aqueous solution of 34.1% by weight of tri-n-butyl-n-pentylammonium bromide, the TiPAB addition rate is 0.25% by weight or more and 5.0% by weight or less. If it is within the range, the supercooling prevention property is excellent, and the latent heat amount in the temperature range of 3 to 15 ° C. is within a practical fluctuation tolerance when the hydrate is used as a heat storage agent or its main component. It can be said that the change of the latent heat amount ratio is 20% or less.

(C) 30% strength aqueous solution of tri-n-butyl-n-pentylammonium bromide Further prepared or prepared by adding tetraisopentylammonium bromide to an aqueous solution of 30% by weight of tri-n-butyl-n-pentylammonium bromide The measurement and evaluation described in the above (1) and (2) were performed on a plurality of raw material solutions. The results are shown in Table 2.
The meanings of TiPAB addition rate, ○, ×, and Δ in Table 2 are the same as in Table 1.

Table 2 shows the following.
[C] When the addition ratio of TiPAB is less than 0.25% by weight with respect to a 30% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, there is no effect of preventing overcooling.
[D] With respect to a 30 wt% aqueous solution of tri-n-butyl-n-pentylammonium bromide, the amount of latent heat is maximum when the addition rate of TiPAB is 0.25 wt%, and the addition rate of TiPAB is 5.0 wt%. If it exceeds, the latent heat ratio is greatly reduced, exceeding the practical fluctuation tolerance (20%).

  From the above results, when adding tetraisopentylammonium bromide to an aqueous solution of 30% by weight of tri-n-butyl-n-pentylammonium bromide, the TiPAB addition ratio is in the range of 0.25% by weight to 5.0% by weight. Therefore, it can be said that the supercooling prevention property is excellent, and the decrease in the latent heat amount in the temperature range of 3 to 15 ° C. is within the practical variation allowable range (the change in the latent heat amount ratio is 20% or less).

(D) 25% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide Further prepared or prepared by adding tetraisopentylammonium bromide to an aqueous solution of 25% by weight of tri-n-butyl-n-pentylammonium bromide The measurement and evaluation described in the above (1) and (2) were performed on a plurality of raw material solutions. The results are shown in Table 3.
The meanings of TiPAB addition rate, ○, ×, and Δ in Table 3 are the same as in Table 1.

Table 3 shows the following.
[E] When the addition ratio of TiPAB is less than 0.25% by weight with respect to a 25% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, there is no effect of preventing overcooling.
[F] With respect to a 25% strength by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, the amount of latent heat is maximum when the addition rate of TiPAB is 0.5% by weight, and the addition rate of TiPAB is 5.0% by weight. If it exceeds, the latent heat ratio is greatly reduced, exceeding the practical fluctuation tolerance (20%).

  From the above results, when adding tetraisopentylammonium bromide to an aqueous solution of 25% by weight of tri-n-butyl-n-pentylammonium bromide, the TiPAB addition rate is in the range of 0.25% by weight to 5.0% by weight. Therefore, it can be said that the supercooling prevention property is excellent, and the decrease in the latent heat amount in the temperature range of 3 to 15 ° C. is within the practical variation allowable range (the change in the latent heat amount ratio is 20% or less).

(E) A 20% strength by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide Further prepared or prepared by adding tetraisopentylammonium bromide to an aqueous solution of 20% by weight of tri-n-butyl-n-pentylammonium bromide. The measurement and evaluation described in the above (1) and (2) were performed on a plurality of raw material solutions. The results are shown in Table 4.
The meanings of TiPAB addition rate, ○, ×, and Δ in Table 4 are the same as in Table 1.

Table 4 shows the following.
[G] When the addition ratio of TiPAB is less than 0.5% by weight with respect to a 20% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, there is no effect of preventing overcooling.
[H] With respect to a 20% strength by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, the amount of latent heat is maximum when the addition rate of TiPAB is 1.5% by weight, and the addition rate of TiPAB is 5.0% by weight. If it exceeds, the latent heat ratio is greatly reduced, exceeding the practical fluctuation tolerance (20%).

  From the above results, when adding tetraisopentylammonium bromide to an aqueous solution of 20% by weight of tri-n-butyl-n-pentylammonium bromide, the TiPAB addition rate is in the range of 0.5% by weight to 5.0% by weight. Therefore, it can be said that the supercooling prevention property is excellent and the decrease in the latent heat amount in the temperature range of 3 to 15 ° C. falls within the practical fluctuation allowable range (the change in the latent heat amount ratio is 20% or less).

(F) 15% strength by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide Further prepared or prepared by adding tetraisopentylammonium bromide to an aqueous solution of 15% by weight of tri-n-butyl-n-pentylammonium bromide. The measurement and evaluation described in the above (1) and (2) were performed on a plurality of raw material solutions. The results are shown in Table 5.
The meanings of TiPAB addition rate, ○, ×, and Δ in Table 5 are the same as in Table 1.

Table 5 shows the following.
[I] When the addition ratio of TiPAB is less than 0.5% by weight with respect to a 15% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, there is no effect of preventing overcooling.
[J] For a 15% strength by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide, the amount of latent heat is maximum when the addition rate of TiPAB is 2.0% by weight, and the addition rate of TiPAB is 5.0% by weight. If it exceeds, the latent heat ratio is greatly reduced, exceeding the practical fluctuation tolerance (20%).

  From the above results, when tetraisopentylammonium bromide is added to an aqueous solution of 15% by weight of tri-n-butyl-n-pentylammonium bromide, the TiPAB addition rate is in the range of 0.5% by weight to 5.0% by weight. Therefore, it can be said that the supercooling prevention property is excellent, and the decrease in the latent heat amount in the temperature range of 3 to 15 ° C. is within the practical variation allowable range (the change in the latent heat amount ratio is 20% or less).

The result of the above [b] [d] [f] [h] [j], that is, the result that the amount of latent heat in the temperature range of 3 to 15 ° C. depends on the addition rate of TiPAB cannot be predicted from the conventional knowledge. It is.

(G) From the results in Tables 1 to 5, when adding tetraisopentylammonium bromide to an aqueous solution of tri-n-butyl-n-pentylammonium bromide of 15 wt% or more and 40 wt% or less, the addition ratio of TiPAB is 0.5 wt. % Over 5.0% by weight, the supercooling prevention property is excellent, and the decrease in the latent heat amount in the temperature range of 3 to 15 ° C is within the practical fluctuation tolerance (change in the latent heat amount ratio). Is 20% or less).

3. About Corrosion Inhibitors In aqueous solutions containing tri-n-butyl-n-pentylammonium bromide as a solute and tetraisopentylammonium bromide added, bromine ions exist and cause corrosion of carbon steel and aluminum. It is preferable to add.

As the corrosion inhibitor, when used in an environment where the heat storage agent is sealed, that is, an environment where dissolved oxygen does not enter, a deoxidation type corrosion inhibitor that consumes dissolved oxygen and suppresses corrosion is preferable. May be a sodium salt or lithium salt of sulfite or thiosulfate, and a film-forming corrosion inhibitor that suppresses corrosion by forming a film that prevents corrosion on the metal surface may be used. Polyphosphate, tripolyphosphate, tetrapolyphosphate, dihydrogen phosphate, pyrophosphate or metasilicate sodium salt, potassium salt, calcium salt, lithium salt, and these film-forming corrosion inhibitors and By using sulfite or thiosulfate as the deoxidizing type corrosion inhibitor described above, the corrosion inhibition effect can be further enhanced.
Further, other corrosion inhibitors applicable to the sealed environment include nitrite, benzotriazole, hydrazine, erythorbate, ascorbate, and saccharide.

When the heat storage agent is used in an open air environment, bromide or sulfate of zinc, magnesium or calcium can be used as a corrosion inhibitor in the open air environment. By adding at least one type of corrosion inhibitor selected from these, hydroxide ions and carbonate ions contained in the solution of the heat storage agent, and zinc ions, magnesium ions or calcium ions of the corrosion inhibitor are added. This results in the formation of carbonates and hydroxides, which can be deposited on the metal surface to form a film to suppress corrosion, and these corrosion inhibitors act as film-forming corrosion inhibitors. Yes.
Add the aforementioned bromide or sulfate of zinc, magnesium or calcium to the heat storage agent, and then add at least one phosphate selected from phosphates such as sodium, potassium, lithium, etc. Acid ions and zinc ions, magnesium ions, or calcium ions are combined to form a phosphate, and this phosphate is deposited on the surface of the metal material to form a coating, thereby inhibiting corrosion. Since phosphates such as sodium, potassium, and lithium have high solubility, they can efficiently form a film and suppress corrosion.

  By adding the above-described corrosion inhibitor to the heat storage agent, it is possible to provide a heat storage agent with less corrosivity without greatly changing the melting point and the heat storage amount.

<Evaluation of corrosion inhibition effect by corrosion inhibitor>
Corrosive to a reference raw material solution in which tetraisopentylammonium bromide is added to a 34.1% by weight aqueous solution of tri-n-butyl-n-pentylammonium bromide in an amount of 0.5% by weight with respect to the weight of the tri-n-butyl-n-pentylammonium bromide solution. Inhibitors were added to evaluate the corrosion inhibition effect in a sealed environment and an open atmosphere.

(A) Corrosion test in a sealed environment Add each corrosion inhibitor shown in Table 6 to the standard raw material solution to prepare the test raw material solutions (1 to 4), and immerse the carbon steel plate and aluminum plate in a sealed container. After holding at 90 ° C. for one week, the weight loss was measured to determine the corrosion rate. The results are also shown in Table 6.

When sodium sulfite is added (test raw material solution 1), the corrosion rate of carbon steel is 0.19 mm / year to 0.06 mm, compared with the case where no corrosion inhibitor is added (test raw material solution 4). The corrosion rate of aluminum has changed from 0.004 mm / year to 0.001 mm / year. In any case, the corrosion rate could be suppressed to 1/3 or less, and the corrosion inhibitory effect was recognized.
Compared with the case where sodium polyphosphate is added (test raw material solution 2) and the case where no corrosion inhibitor is added (test raw material solution 4), the corrosion rate of carbon steel is 0.19 mm / year to 0.000. The corrosion rate of aluminum was changed from 0.004 mm / year to 0.001 mm / year. In any case, the corrosion rate could be suppressed to 1/3 or less as in the case of adding sodium sulfite, and the corrosion inhibitory effect was recognized.
When sodium sulfite and sodium polyphosphate are used together (test raw material solution 3), the corrosion rate of carbon steel is 0.19 mm / year, compared to the case where no corrosion inhibitor is added (test raw material solution 4). From 0.04 mm / year, the corrosion rate of aluminum was changed from 0.004 mm / year to 0.001 mm / year. Carbon steel showed a higher corrosion inhibitory effect than when each corrosion inhibitor was used alone.
In either case, both carbon steel and aluminum exhibited a form of general corrosion, and no local corrosion occurred. In addition, it confirmed that there was an effect which can fully suppress corrosion similarly with the other corrosion inhibitor mentioned above.

(B) Corrosion test in open air environment Each corrosion inhibitor shown in Table 7 is added to the reference raw material solution to prepare the test raw material solution (5-8), and the Liebig condenser is attached to prevent evaporation. While the carbon steel plate and the aluminum plate were immersed in a container in which the test raw material solution was in contact with the atmosphere and held at 90 ° C. for 1 week, the weight loss was measured to determine the corrosion rate. The results are also shown in Table 7.

In carbon steel, when zinc sulfate is added (test raw material solution 5), the corrosion rate is 0.34 mm / year to 0.13 mm, compared with the case where no corrosion inhibitor is added (test raw material solution 8). / Year, it was possible to suppress the corrosion rate to half or less, and the corrosion inhibitory effect was recognized. In the case where no corrosion inhibitor is added in aluminum (test raw material solution 8), the corrosion rate is 0.007 mm / year and pitting corrosion occurs, but in the case where zinc sulfate is added (test raw material solution 5). The corrosion rate was 0.002 mm / year, no pitting corrosion was observed, the corrosion rate could be suppressed to 1/3 or less, and pitting corrosion was prevented and a corrosion inhibiting effect was recognized.
Compared to the case where sodium polyphosphate is added (test raw material solution 6) and the case where no corrosion inhibitor is added (test raw material solution 8), the corrosion rate of carbon steel is 0.34 mm / year to 0.000. At 16 mm / year, the corrosion rate of aluminum was changed from 0.007 mm / year to 0.003 mm / year to prevent pitting corrosion. In either case, the corrosion rate could be suppressed to half or less, and a corrosion suppressing effect was recognized.
In the case of using zinc sulfate and sodium polyphosphate together (test raw material solution 7), the corrosion rate of carbon steel is 0.34 mm / year compared to the case where no corrosion inhibitor is added (test raw material solution 8). The corrosion rate of aluminum was 0.007 mm / year to 0.001 mm / year, preventing pitting corrosion. Carbon steel showed a higher corrosion inhibitory effect than when each corrosion inhibitor was used alone.
Even when any corrosion inhibitor was added, both carbon steel and aluminum exhibited a form of general corrosion, and local corrosion such as pitting corrosion did not occur. In particular, pitting corrosion leads to leakage of the heat storage material inside the pipe and the container, so that the effect of suppressing pitting corrosion is great by adding a corrosion inhibitor. In addition, it confirmed that there was an effect which can fully suppress corrosion similarly with the other corrosion inhibitor mentioned above.

4). About the preparation method of the aqueous solution for producing the heat storage agent or its main component (a) An aqueous solution of tri-n-butyl-n-pentylammonium bromide prepared to a concentration of 15 wt% or more and 34.1 wt% (harmonic concentration) or less Then, an aqueous solution for producing a hydrate or a heat storage agent or a main component thereof is prepared by adding an aqueous solution of tetraisopentylammonium bromide or tetraisopentylammonium bromide. At this time, the amount of tetraisopentylammonium bromide or an aqueous solution of tetraisopentylammonium bromide is such that the weight ratio of tetraisopentylammonium bromide to the aqueous solution of tri-n-butyl-n-pentylammonium bromide is 0.5% or more. Add so that it is less than 0.0%. By preparing in this way, a hydrate that is excellent in supercooling prevention and has a small decrease in latent heat in the temperature range of 3 to 15 ° C., which is a heat storage agent or its main component is obtained. be able to.

The thermal energy corresponding to the latent heat accumulated by the hydrate produced by cooling the aqueous solution for producing hydrate is maximized when the concentration of guest molecules in the aqueous solution is a harmonic concentration. Therefore, in order to increase the latent heat amount of the heat storage agent containing hydrate as a main component, it is preferable that the aqueous solution of tri-n-butyl-n-pentylammonium bromide has a harmonic concentration (34.1% by weight).
If an aqueous solution of tri-n-butyl-n-pentylammonium bromide having a concentration lower than or higher than the harmonic concentration is used, the melting point of the hydrate produced by cooling the aqueous solution for producing the hydrate can be made lower than the harmonic melting point.

(I) When tetraisopentylammonium bromide is added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide as a supercooling inhibitor, tetraisopentylammonium bromide powder may be added, or tetraisobromide bromide. You may add as an aqueous solution of pentylammonium. In order to prepare an aqueous solution for producing the heat storage agent or its main component, an aqueous solution of tri-n-butyl-n-pentylammonium bromide and an aqueous solution of tetraisopentylammonium bromide may be mixed, or tri-n-bromide. Water may be added to butyl n-pentylammonium powder and tetraisopentylammonium bromide powder and mixed, or these powders may be added to water and mixed. Needless to say.

(C) In order to prevent supercooling of the aqueous solution of tri-n-butyl-n-pentylammonium bromide, disodium hydrogen phosphate may be added as a supercooling inhibitor.
By adding tetraisopentylammonium bromide and disodium hydrogen phosphate as a supercooling inhibitor in combination, supercooling can be prevented more effectively. For example, when adding tetraisopentylammonium bromide to an aqueous solution of tri-n-butyl-n-pentylammonium bromide, disodium hydrogen phosphate is added to the aqueous solution of tri-n-butyl-n-pentylammonium bromide, and tetraisobromide bromide is added. When used in combination with pentylammonium, the effect of preventing overcooling is enhanced as compared with the case where only tetraisopentylammonium bromide is added. Therefore, according to this combined use, even if the addition rate of tetraisopentylammonium bromide is reduced, the same level of supercooling prevention effect can be obtained, and due to the addition of tetraisopentylammonium bromide, A change in the amount of latent heat of the hydrate or the heat storage agent containing this as a main component can be suppressed to be small.
4. Tetraisopentylammonium bromide added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide has a weight ratio of tetraisopentylammonium bromide to an aqueous solution of tri-n-butyl-n-pentylammonium bromide of 0.5% or more. When it is within the range of 0% or less, the amount of disodium hydrogen phosphate added is preferably 0.1 to 2.0% by weight with respect to the aqueous solution of tri-n-butyl-n-pentylammonium bromide. It is.

(D) In order to prevent overcooling of an aqueous solution of tri-n-butyl-n-pentylammonium bromide, a metal salt of an aliphatic carboxylic acid such as sodium stearate or potassium palmitate may be added as a supercooling inhibitor. .
Tetraisopentylammonium bromide and a metal salt of an aliphatic carboxylic acid can be added together as a supercooling inhibitor to prevent supercooling more effectively. For example, when tetraisopentylammonium bromide is added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide, a metal salt of an aliphatic carboxylic acid is added to the aqueous solution of tri-n-butyl-n-pentylammonium bromide, and bromide is added. When used in combination with tetraisopentylammonium, the effect of preventing overcooling is enhanced as compared with the case where only tetraisopentylammonium bromide is added. Therefore, according to this combined use, even if the addition rate of tetraisopentylammonium bromide is reduced, the same level of supercooling prevention effect can be obtained, and due to the addition of tetraisopentylammonium bromide, A change in the amount of latent heat of the hydrate or the heat storage agent containing this as a main component can be suppressed to be small.
4. Tetraisopentylammonium bromide added to an aqueous solution of tri-n-butyl-n-pentylammonium bromide has a weight ratio of tetraisopentylammonium bromide to an aqueous solution of tri-n-butyl-n-pentylammonium bromide of 0.5% or more. When it is within the range of 0% or less, the addition amount of the metal salt of the aliphatic carboxylic acid is 0.1 to 2.0% by weight with respect to the aqueous solution of tri-n-butyl-n-pentylammonium bromide. Is preferred.

  Finally, the technical scope of the present invention is not limited by the above embodiments, and can be implemented in various forms without changing the gist of the present invention. For example, an embodiment in which a substance not specified above is added belongs to the technical scope of the present invention as long as the efficacy of the present invention is not inhibited. The technical scope of the present invention extends to an equivalent range.

Claims (11)

An aqueous solution for clathrate hydrate formation, comprising tri-n-butyl-n-pentylammonium bromide as a solute and tetraisopentylammonium bromide added as a supercooling inhibitor. The inclusion according to claim 1, wherein a weight ratio of tetraisopentylammonium bromide to an aqueous solution containing tri-n-butyl-n-pentylammonium bromide as a solute is 0.5% or more and 5.0% or less. Aqueous solution for hydrate formation. The concentration of tri-n-butyl-n-pentylammonium bromide is 15 to 34.1% by weight, and the weight ratio of tetraisopentylammonium bromide to an aqueous solution containing tri-n-butyl-n-pentylammonium bromide as a solute is 0. The aqueous solution for clathrate hydrate formation according to claim 1, wherein the aqueous solution is 0.5% or more and 5.0% or less. The aqueous solution for clathrate hydrate formation according to any one of claims 1 to 3, wherein a corrosion inhibitor is added. The heat storage agent characterized by including the clathrate hydrate produced | generated when the aqueous solution for clathrate hydrate production | generation in any one of Claim 1 thru | or 4 is cooled below to hydrate formation temperature . The clathrate hydrate produced when the aqueous solution for clathrate hydrate formation according to any one of claims 1 to 4 is cooled to a hydrate production temperature or lower is dispersed in the aqueous solution or an aqueous solvent. A heat storage agent comprising a slurry obtained by suspending. A heat storage agent comprising tri-n-butyl-n-pentylammonium bromide, tetraisopentylammonium bromide as a supercooling inhibitor, and water. A package comprising the steps of: preparing an aqueous solution for producing clathrate hydrate according to any one of claims 1 to 4; and cooling the aqueous solution to produce clathrate hydrate. A method for producing a wet hydrate or a slurry thereof. The aqueous solution for clathrate hydrate formation according to any one of claims 1 to 4 is cooled to generate clathrate hydrate, thereby accumulating heat energy and melting the clathrate hydrate produced. A heat storage / dissipation method characterized in that heat energy is released. A method for preparing an aqueous solution for producing a latent heat storage agent or a main component thereof, comprising a step of adding tetraisopentylammonium bromide to an aqueous solution of tri-n-butyl-n-pentylammonium bromide. Preparation method of aqueous solution. The method for preparing an aqueous solution according to claim 10, wherein the weight ratio of tetraisopentylammonium bromide to the aqueous solution of tri-n-butyl-n-pentylammonium bromide is 0.5% or more and 5.0% or less.